class phone:
    IMEI=None
    producer=None
    def call_by_4g(self):
        print("4g通话")

class nfc:
    def Start(self):
        print("开启nfc")

class xiaomi_phone(phone,nfc):
    pass

my_phone=xiaomi_phone()
my_phone.call_by_4g()
my_phone.Start()